I don't know about cute, but a majority casual gamers online are female. Google "casual gaming female" and there are reports across several years. Some of them have the proportion as high as 70%.

If you dig further into the market research, though, you'll find that the majority of those are 40-something housewives in middle America. Basically the same population who watches daytime soap operas. Actually, I suspect the Internet casual game marketplace will kill the soap opera.

So no, there are not a bunch of cute girls on casual gaming sites. Most of the cute girls seem to be on TV fansites of shows popular with teens and 20-somethings.